Naked collation package

ABSTRACT

The invention generally relates to a naked collation package comprising an arrangement of individual packages, individually packaged in a polyolefinic filmic material, that are packed together in said naked collation package in a naked collation film, and there being no seal between the naked collation film and the filmic material of the individual packages. A method for forming the naked collation package and a method for manufacturing the naked collation package are also disclosed.

FIELD

The present invention relates to a naked collation package and to amethod for its manufacture.

BACKGROUND

U.S. Pat. No. 6,887,582 discloses a polyolefin multi-layer film for coldseal cohesive applications, including a first polyolefin skin layercomprising a blend of ethylene propylene random copolymer andmetallocene catalysed plastomer.

U.S. Pat. No. 6,451,426 discloses a sealable film used for packaging,particularly in the form of bags, comprising an olefin polymer layer anda sealing layer, and a separable block copolymer layer therebetween toprovide peelability.

U.S. Pat. No. 5,898,050 discloses a polyolefin composition for preparinga polyolefin film having heat sealing properties.

U.S. Pat. No. 5,792,549 discloses a coextruded biaxially orientedpolyolefin packaging film having a cold seal release layer, a core layerand a cold seal receptive skin layer.

EP-B-0963408 discloses an oriented coextruded multilayer film for heatshrinkable packaging comprising a copolyethylene outer layer coextrudedwith a polypropylene core layer.

U.S. Pat. No. 6,979,495 discloses a biaxially oriented multilayer filmcomprising a core layer of syndiotactic polypropylene homopolymer and atleast one additional layer adjacent the core layer comprising a polymerwhich is an ethylene or a propylene homopolymer, ethylene copolymer orterpolymer containing comonomers of propylene and/or butane-1.

WO-A-01/49487 discloses a multilayer polymeric film for packing cassettetapes, comprising a core layer containing polypropylene, polymericmodifier containing polyolefin(s), and hydrocarbon resin between a pairof skin layers.

U.S. Pat. No. 6,908,687 discloses a heat shrinkable polymeric film foruse in label applications comprising a shrink control layer including ablend of primary polymeric component and modifier component comprisingethylene plastomer, polypropylene plastomer or ethylene/propylenecopolymer.

WO-A-04/003874 discloses a machine direction oriented polymeric film foradhesive labels comprising polypropylene homopolymers and/or copolymershaving preset melt flow rates, and olefin elastomers.

EP-B-0622187 discloses a biaxially oriented polypropylene film having apolypropylene base layer and an outer layer containing polypropylenehomo-, co, or ter-polymer and HDPE or a blend to provide shrinkagecharacteristics.

EP-B-0622186 discloses biaxially oriented polypropylene films for shrinkwrapping, having a polypropylene base layer and outer layer(s)containing an olefin co- or terpolymer and HDPE.

WO-A-03/089336 discloses a method of packing packets of cigaretteswherein an ordered group of individual packets is packed solely in asheet of transparent heat-seal plastic packing material, which is foldedabout the ordered group to form a tubular wrapping. A girth seal is thenprovided to seal the tube, and envelope seals at each end of thepackage. This type of packaging is known in the art as naked collation,because the individual packets are packaged only in the film and not in,for example, a larger box which is then wrapped in the film. Shrinknaked collation refers in the art to this type of package wherein thefilm is shrinkable to wrap more tightly the collated packets oncesealed.

U.S. Pat. No. 6,358,579 discloses another naked collation type packagingwherein the packaging film is a polyolefin film with modifiedpolyolefinic sealable layers. The sealable outer layers comprisecopolyester and the combined film is to seal to itself, but not to thebiaxially oriented polypropylene films of the individual packages.

A multipack system in which individual packaging takes place in abiaxially stretch-oriented polypropylene film having modifiedpolyolefinic heat-sealing layers is disclosed in DE3635928.

EP1431028 discloses a polypropylene film or laminate, in which if thefilm/laminate is heat-sealable the inside of the film is coated locallywith heat-resistant varnish over areas affected by sealing, whereas ifthe film/laminate is not heat-sealable a heat-sealable varnish isapplied to the sealing points.

DETAILED DESCRIPTION

The present invention is primarily concerned with overwrap films fornaked collation. Naked collation is an effective way to reduce packagingcosts and materials. When a number of individually packaged articles(cigarette packs, for example) are to be grouped together and packagedas a larger bundle for distribution or for bulk retail, it is usual forthe individual packages to be placed in a larger box or carton, beforethen being wrapped. Naked collation eliminates the need for the box orcarton. However, one of the problems of naked collation in film wrappingis that in generating the collated package it is necessary to seal thefilm package. This raises the prospect of the collated package filmsealing not only to itself but also to the film used to wrap eachindividual packet. In the cigarette industry, wherein the individualpacks tend to be wrapped in polypropylene film, this is a particularproblem. The manufacturer would often prefer to use polypropylene filmfor its collated bundle, taking advantage of the favorable optical andmechanical properties of such films, but in that case risks sealing thecollation film also to the film of the individual packs. Such problemshave in the past been addressed by providing the polypropylenic overwrapfilm for naked collation with an acrylic coating, which seals well toitself but not to the polypropylene wrapping of the individual packs.However, acrylic coatings add cost to the film manufacturing process,both in terms of the material used to provide the coating and, perhapsmore importantly, in necessitating a coating operation followingextrusion of the film.

It is an object of the present invention to provide an improved nakedcollation film in polyolefin packaging, in particular one which avoidsthe need for an acrylic coating.

According to the present invention there is provided a method forforming a naked collation package comprising:

providing an arrangement of packages individually wrapped in a filmicpolyolefinic material; providing a naked collation film for nakedlywrapping said individually wrapped packages, the naked collation filmcomprising a polyolefinic core layer C, a polyolefinic inner sealinglayer A on the inner surface of the naked collation film and apolyolefinic outer sealing layer B on the outer surface of the nakedcollation film, the polyolefinic material of the inner sealing layer Abeing selected for sealing incompatibility with the filmic polyolefinicmaterial of the individually wrapped packages under a specified sealingcondition, and the polyolefinic material of the outer sealing layer Bbeing selected for sealing compatibility with B and for sealingcompatibility with A under the selected sealing condition;

arranging the individually wrapped packages in an ordered configurationin contact with polyolefinic sealing layer A of the naked collationfilm;

wrapping the naked collation film around the ordered configuration ofindividually wrapped packages to form a film tube with overlappingedges;

forming a girth seal by sealing together the overlapping edges of thefilm tube, without sealing inner sealing layer A to the filmic polymericmaterial of the individually wrapped packages; and forming envelopeseals at each end of the package by folding in the film tube and sealingthe folded ends, without sealing inner sealing layer A to the filmicpolymeric material of the individually wrapped packages.

Preferably the girth seal is formed A to B. The envelope seals may beformed B to B and/or A to B and/or A to A, and combinations of two ormore thereof.

Preferably the external surface of the filmic polyolefinic material ofthe individually wrapped packages comprises at least one polyolefiniccomponent derived from a monomeric olefin having a carbon chain lengthx, and the polyolefinic material of the inner sealing layer A comprisesat least one polyolefinic component derived from a monomeric olefinhaving a carbon chain length y, y being different from x. Morepreferably, the polyolefinic material of the outer sealing layer B alsocomprises at least one polyolefinic component derived from a monomericolefin having a carbon chain length y. Thus, in the case where thesurface polyolefinic material of the individually wrapped packagescomprises a polyethylenic component, the polyolefinic material of theinner sealing layer A preferably comprises a polypropylenic componentand/or a polybutylenic component. Preferably in this case thepolyolefinic material of the outer sealing layer B also comprises apolypropylenic component and/or a polybutylenic component. In the casewhere the surface polyolefinic material of the individually wrappedpackages comprises a polypropylenic component, the polyolefinic materialof the inner sealing layer A preferably comprises a polyethyleniccomponent and/or a polybutylenic component. Preferably in this case thepolyolefinic material of the outer sealing layer B also comprises apolyethylenic component and/or a polybutylenic component. In the casewhere the surface polyolefinic material of the individually wrappedpackages comprises a polybutylenic component, the polyolefinic materialof the inner sealing layer A preferably comprises a polyethyleniccomponent and/or a polypropylenic component. Preferably in this case thepolyolefinic material of the outer sealing layer B also comprises apolyethylenic component and/or a polypropylenic component.

For the avoidance of doubt, it is mentioned that when the externalsurface of the filmic polyolefinic material of the individually wrappedpackages comprises at least one polyolefinic component derived from amonomeric olefin having a carbon chain length x, and the polyolefinicmaterial of the inner sealing layer A comprises at least onepolyolefinic component derived from a monomeric olefin having a carbonchain length y, y being different from x, the polyolefinic material ofthe inner sealing layer A may additionally comprise at least onepolyolefinic component derived from a monomeric olefin having a carbonchain length x. In this case, the polyolefinic material of the innersealing layer A comprises at least two polyolefinic components, onebeing derived from a monomeric olefin having a carbon chain length y andthe other being derived from a monomeric olefin having a carbon chainlength x. The polyolefinic material of the outer sealing layer B mayalso additionally comprise at least one polyolefinic component derivedfrom a monomeric olefin having a carbon chain length x, in which casethe polyolefinic material of the outer sealing layer B also comprises atleast two polyolefinic components, one being derived from a monomericolefin having a carbon chain length y and the other being derived from amonomeric olefin having a carbon chain length x. It is also contemplatedwithin the scope of the invention to provide a sealing layer and/or afilmic polyolefinic material having a polymeric component derived fromplural monomeric sources (for example a polypropylene/polyethylenerandom or block copolymer, and/or a blend of polypropylene andpolyethylene), in which case provided that the sealing layer is derivedfrom at least one monomeric component which has a different chain lengthfrom at least one monomeric originating component of the filmicpolyolefinic material, then the condition of the invention is realized.It will be appreciated that in this case the filmic polyolefinicmaterial and the material of the sealing layer may consist of orcomprise the same polyolefinic material, for example a block or randomcopolymer or blend derived from plural monomeric sources wherein atleast one monomeric source (for example ethylene) is of different chainlength from at least one other monomeric source (for example propylene).

Preferably both x and y are from 2 to 4, although x and y must bedifferent in this embodiment of the invention.

Accordingly, the invention provides a means for forming a nakedcollation package in which the naked collation film is renderedincompatible (for sealing purposes at the sealing condition) with thepolyolefinic (especially polypropylenic) material wrapping theindividual packets. The naked collation film has sealing compatibilitywith itself (A to B, A to A and/or B to B) at the sealing condition butis sealingly incompatible (at the sealing condition) with the filmicpolyolefinic material of the individually wrapped packages. One way inwhich such sealing incompatibility can be provided is by providing in atleast the inner sealing layer of the naked collation film at least onepolyolefinic material derived from a monomer of different chain lengthfrom a monomer from which at least one polyolefinic material in thefilmic material of the wrapped individual packages is derived. Anothersuitable way of achieving such sealing compatibility is to select thematerial of at least the inner sealing layer (and/or the outer sealinglayer) to have a low seal threshold, at which the sealing layer will besealingly compatible with itself at the sealing condition and/or withthe other sealing layer of the naked collation film, but will besealingly incompatible under that condition with the polyolefinic filmicmaterial of the wrapped individual packages. In this case the nakedcollation film is designed to have a very low seal initiationcharacteristic because it is formed from at least one polymer having alow heat seal threshold. Sealing at a low temperature prevents the nakedcollation film from sticking to the unit wraps.

Accordingly, the invention provides a method as hereinbefore describedfor forming a naked collation package in which the polymeric material ofthe inner and/or outer sealing layer comprises at least one polyolefiniccomponent having a low heat seal threshold.

By “low heat seal threshold”, it is preferably meant that the sealinglayer comprising the polyolefinic material having the low heat sealthreshold will seal to itself and/or to the other sealing layer of thenaked collation film at a temperature of less than 135° C., preferablyless than 130° C., more preferably less than 125° C., still morepreferably less than 120° C., even more preferably less than 115° C. andmost preferably less than 110° C. when subjected to a sealing conditionof for example 5 psi at a 0.2 s dwell time. The sealing condition informing the naked collation package of the invention may be selected tocorrespond the said sealing temperature, or to be greater than it,provided that the sealing condition is not selected to be so great thatsealing between the inner sealing layer of the naked collation film andthe polyolefinic filmic material of the wrapped individual packages willbegin to occur. The heat seal strength of the inner sealing layer toitself and/or to the outer sealing layer at the selected sealingcondition is preferably above 100 g/25 mm, more preferably above 200g/25 mm, still more preferably above 300 g/25 mm and most preferablyabove 400 g/25 mm.

The heat seal threshold of the or each sealing layer of the nakedcollation film to itself and/or to the other sealing layer of the nakedcollation film should in any event be lower than the heat seal thresholdof the said sealing layer to the polyolefinic filmic material of theunit wraps, preferably substantially lower, for example at least about5° C. lower, preferably at least about 10° C. lower, more preferably atleast 15° C. lower. At the selected sealing condition the seal strengthof the or each sealing layer of the naked collation film to itselfand/or to the other sealing layer of the naked collation film should behigher than the seal strength of the said sealing layer to thepolyolefinic filmic material of the unit wraps, preferably substantiallyhigher, for example at least about 50 g/25 mm higher, preferably atleast about 100 g/25 mm higher, more preferably at least about 150 g/25mm higher.

By “sealing incompatibility” or “sealingly incompatible”, it ispreferably meant that the seal strength at the sealing condition is lessthan 100 g/25 mm, preferably less than 80 g/25 mm, more preferably lessthan 60 g/25 mm, still more preferably less than 40 g/25 min, yet morepreferably 30 g/25 mm, even more preferably less than 20 g/25 mm andmost preferably less than 10 g/25 mm, or even less than 5 g/25 mm, orclose to 0 g/25 mm or zero.

The sealing layer of the film may optionally be corona dischargetreated, or treated in some other way further to enhance the sealingincompatibility between the sealing layer and the filmic polyolefinicmaterial.

The filmic polyolefinic material may be of any known construction,including monolayer and multilayer, but in order to inform the selectionof the polyolefinic material of the inner sealing layer A for sealingincompatibility with the filmic material it is generally only necessary,or primarily necessary, to consider only the external outer later of thefilmic polyolefinic. In this sense “sealing incompatibility” refers to asubstantial absence of sealing at the selected sealing condition betweenthe inner sealing layer A and the external outer surface of the filmicpolyolefinic material of the individually wrapped packages.

The invention also provides a naked collation package comprising anarrangement of individual packages, individually packaged in apolyolefinic filmic material, that are packed together in said nakedcollation package in a naked collation film, wherein the naked collationfilm comprises a sealable polyolefin film having a polyolefinic corelayer C, an polyolefinic inner sealing layer A and a polyolefinic outersealing layer B, the polyolefinic material of the inner sealing layer Abeing selected for sealing incompatibility with the filmic polyolefinicmaterial of the individual packages under a specified sealing condition,and the polyolefinic material of the outer sealing layer B beingselected for sealing compatibility with B and for sealing compatibilitywith A under the selected sealing condition, the individual packagesbeing arranged in an ordered configuration inside the package and withthe naked collation film wrapped around the ordered configuration ofindividual packages and sealed to itself (A to B) at a girth seal, andsealed to itself (B to B and optionally A to B and/or A to A) atenvelope seals at each end of the package, there being no seal betweenthe naked collation film and the filmic material of the individualpackages.

The sealing condition may be selected by the assembler of the nakedcollation package and will generally comprise conditions of elevatedtemperature and/or pressure and a dwell time for the sealing operation.Typically the sealing temperature will be above 80° C., for exampleabove 85° C., or even above 90° C.

Sometimes seal temperatures in excess of 95° C. or even 100° C. may beused.

Typically it is desirable for the sealing temperature to be below acertain level also. An excessive sealing temperature may cause sealingof the naked collation film to the individual packages. Generally thesealing temperature will be below 200° C., more often lower, such asbelow 175° C., below 150° C. or below 140° C.

Usually it is preferable for the sealing temperature not to exceed 130°C. The sealing pressure will typically be above 2 psi, often betweenabout 5 psi and 25 psi for example. Dwell times may be selected inaccordance with well known principles and will generally be from atleast about 0.05 s to about 2 s, for example from 0.075 s to about 1 s,preferably from about 0.1 s to about 0.5 s. The sealing layers arepreferably formed as coat layers, or coatings, on opposite surfaces ofthe core layer C. These layers may be formed by coextrusion with thecore layer, by the subsequent application of one of more coats onto thesurface of the already formed core layer, by extrusion coating, or by acombination thereof. Generally it is preferred that the sealing layersbe coextruded together with the core layer in manufacture of the nakedcollation film.

The sealing layers will generally comprise one or more polyolefinichomopolymers, one or more polyolefinic copolymers, or mixtures of two ormore thereof. By “copolymers” in this sense is meant any number ofconstituent polymer parts—so that bipolymers, terpolymers and copolymersof four or more constituent polymer parts are all included, for example.Both random and block copolymers are included in this definition, andthe sealing layers may additionally or alternatively comprise blends ofone or more homopolymers, copolymers or mixtures thereof. The sealinglayer material for the sealing layers A and B may be the same ordifferent.

The core layer is polyolefinic and may also comprise one or morehomopolymers, one or more copolymers, or mixtures of two or morethereof. Preferably however, the core layer comprises a homopolymer,more preferably polypropylene, most preferably biaxially orientedpolypropylene. The material of the core layer may however be blendedwith one or more further materials to select if desired additional oralternative functionality or aesthetics. It will be understood that thenaked collation film may comprise additional layers as well as thehitherto identified core and sealing layers C, A and B. Such additionallayers may for example include lamination layers, printable layers, UVbarrier layers, oxygen permeability or barrier layers, water vapourpermeability or barrier layers and the like. Such additional layers maybe provided also by coextrusion, by post-coextrusion coating, bycoextrusion coating or by combinations of two or more thereof.

The naked collation film may comprise, in its core layer and/or in oneor more of its sealing layers and/or in any additional layer(s)functional materials for other purposes in relation to the functional oraesthetic characteristics of the film. Suitable functional materials maybe selected from one or more of the following, mixtures thereof and/orcombinations thereof: UV absorbers, dyes; pigments, colorants,metallised and/or pseudo-metallised coatings; lubricants, anti-staticagents (cationic, anionic and/or non-ionic, e.g. [rho]oly-(oxyethylene)sorbitan monooleate), anti-oxidants (e.g. phosphorous acid, tris(2,4-di-tert-butyl phenyl) ester), surface-active agents, stiffeningaids, slip aids (for example hot slips aids or cold slip aids whichimprove the ability of a film to slide satisfactorily across surfaces atabout room temperature, e.g. micro-crystalline wax; gloss improvers,prodegradants, barrier coatings to alter the gas and/or moisturepermeability properties of the film (such as polyvinylidene halides,e.g. PVdC); anti-blocking aids (for example microcrystalline wax, e.g.with an average particle size from about 0.1 to about 0.6 [mu]m); tackreducing additives (e.g. fumed silica, silica, silicone gum);particulate materials (e.g. talc); additives to increase COF (e.g.silicon carbide); additives to improve ink adhesion and/or printability,additives to increase stiffness (e.g. hydrocarbon resin); additives toincrease shrinkage (e.g. hard resin).

Some or all of the additives listed above may be added together as acomposition to coat the films of the present invention and/or faint anew layer which may itself be coated and/or may form the outer orsurface layer of the sheet. Alternatively, some or all of the precedingadditives may be added separately and/or incorporated directly into thebulk of the core layer optionally during film formation (e.g. as part ofthe original polymer composition), and thus they may or may not formlayers or coatings as such.

Films of the invention can also be made by the laminating of twoco-extruded films. Application of the outer layer(s) onto the core layeris conveniently effected by any of the laminating or coating techniquesconventionally employed in the production of composite multi-layerfilms. Preferably, however, one or more outer layers are applied to thesubstrate by a co-extrusion technique in which the polymeric componentsof the core and outer layers are co-extruded into intimate contact whileeach is still molten. Preferably the co-extrusion is effected from amulti channel annular die so designed that the molten polymericcomponents constituting individual layers of the composite film merge attheir boundaries within the die to form a single composite structurewhich is then extruded from a common die orifice in the form of atubular extrudate. It will be appreciated that any other shape ofsuitable die could also be used such as flat die.

The polymeric film can be made by any process known in the art,including, but not limited to, cast sheet, cast film, or blown film.This invention may be particularly applicable to films comprisingcavitated or non-cavitated polypropylene films, with a block copolymerpolypropylene/polyethylene core and skin layers with a thicknesssubstantially below that of the core layer and formed for example fromrandom co-polymers of ethylene and propylene or random terpolymers ofpropylene, ethylene and butylene. The film may comprise a biaxiallyorientated polypropylene (BOPP) film, which may be prepared as balancedfilms using substantially equal machine direction and transversedirection stretch ratios, or can be unbalanced, where the film issignificantly more orientated in one direction (MD or TD). Sequentialstretching can be used, in which heated rollers effect stretching of thefilm in the machine direction and a stenter oven is thereafter used toeffect stretching in the transverse direction. Alternatively,simultaneous stretching, for example, using the so-called bubbleprocess, or simultaneous draw stenter stretching may be used.

The films used in accordance with the present invention can be of avariety of thicknesses according to the application requirements. Forexample they can be from about 10 to about 240 μm thick, preferably fromabout 12 to 50 μm thick, and most preferably from about 15 to about 30μm thick.

In a multi-layer film in accordance with the invention having at least acore layer, an inner sealing layer and an outer sealing layer, eachsealing layer may independently have a thickness of from about 0.05 μmto about 2 μm, preferably from about 0.075 μm to about 1.5 μm, morepreferably from about 0.1 μm to about 1.0 μm, most preferably from about0.15 μm to about 0.5 μm. The inner and/or outer sealing layers may beink printable, either inherently or with the aid of a suitabletreatment, corona discharge treatment for example.

The invention is further illustrated by reference to the followingexamples, which are by way of illustration only, and are not limiting tothe scope of the invention described herein.

Examples 1 to 8 Preparation of Film

A three layer polymeric tube was formed by coextruding a core layer (ofpolypropylene homopolymer with a layer ofpolyethylene/polypropylene/polybutylene terpolymer (a random copolymer)as a skin layer on both sides of the core layer, Prior to coextrusionthe skin layer materials for the inner and outer layers were blendedwith further functional materials intended in accordance with theinvention to provide selective sealability properties to the film. Thetube was cooled and subsequently reheated before being blown to producea three layer biaxially oriented film tube. The film tube was thenspliced separated in opposite directions to form a three layer biaxiallyoriented film having an inner layer of the approximate thicknessspecified below, a core layer of approximately 23 to 24 μm thickness,and an outer layer of the approximate thickness specified below.

The film compositions are presented in Table 1:

TABLE 1 Sample Details Discharge Example Inner Coat Outer Coat Treatment1 0.17 μm thickness, 0.25 μm thickness, Treated comprising a compoundedcomprising a compounded masterbatch containing masterbatch containingExact 0203* + 0.2% silica Exact 8203* + 0.5% silica + 0.5% silicone gum2 0.17 μm thickness, 0.25 μm thickness, Non comprising a compoundedcomprising a compounded Treated masterbatch containing masterbatchcontaining Exact 0203* + 0.2% silica Exact 8203* + 0.5% silica + 0.5%silicone gum 3 0.35 μm thickness, 0.25 μm thickness, Treated comprisinga physical comprising a physical blend of SPX78J3^(#) + blend ofSPX78J3^(#) + 0.1% 0.04% silica + 0.175% silica silicone gum + 10%C600H2^(‡) 4 0.35 μm thickness, 0.25 μm thickness, Non comprising aphysical comprising a physical Treated blend of SPX78J3^(#) + blend ofSPX78J3^(#) + 0.1% 0.04% silica + 0.175% silica silicone gum + 10%C600H2^(‡) 5 0.25 μm thickness, 0.25 μm thickness, Treated comprising acompounded comprising a physical masterbatch of C600H2^(‡) + blend ofSPX78J3^(#) + 0.1% 1.75% silicone gum + silica 0.4% silica 6 0.25 μmthickness, 0.25 μm thickness, Non comprising a compounded comprising aphysical Treated masterbatch of C600H2^(‡) + blend of SPX78J3^(#) + 0.1%1.75% silicone gum + silica 0.4% silica 7 0.25 μm thickness, 0.25 μmthickness, Treated comprising C600H2^(‡) comprising a physical blend ofSPX78J3^(#) + 0.1% silica 8 0.25 μm thickness, 0.25 μm thickness, Noncomprising C600H2^(‡) comprising a physical Treated blend ofSPX78J3^(#) + 0.1% silica *Exact 0203 and 8203 are octene-1 plastomersavailable from Dex Plastomers CBS-Weg 2, Heerlen, P.O. Box 6500, 6401 JH Heerlen, The Netherlands. ^(#)SPX78J-3 is a low seal threshold meltblend of a copolymer and a terpolymer available from Sumitomo ChemicalCo. Ltd, 27-1, Shinkawa 2 - chome, Chuo-ku, Tokyo, 104-8260, Japan.C600H2± is a propylene butylene copolymer supplied by Hyosung (Korea),Hyosung Bldg. 450 Gongdeok-dong, Mapo-gu, Seoul (121-720).

Certain mechanical and optical properties of the films were measured,with the following results:

TABLE 2 Optics Narrow Wide Gloss % (45°) Angle Angle Example IN OUT Haze(%) Haze (%) 1 98.5 98.2 2.8 1.5 2 89.3 83.9 2.0 3.3 3 99.8 99.0 2.1 1.14 100.4 100.4 2.0 1.6 5 91.2 85.9 2.5 2.8 6 92.3 85.7 1.9 3.0 7 98.597.9 2.2 1.4 8 99.5 99.5 2.0 1.6

TABLE 3 Coefficient of Friction Samples were tested on the Messmer SlipTester using the Clampmod method. Example IN/IN OUT/OUT IN/OUT IN/METALOUT/METAL Static 1 0.39 0.53 0.36 0.32 0.30 2 0.29 0.43 0.31 0.21 0.23 30.57 0.56 0.47 0.52 0.41 4 0.45 0.50 0.46 0.28 0.28 5 0.40 0.55 0.440.32 0.37 6 0.28 0.41 0.30 0.21 0.24 7 0.53 0.56 0.57 0.50 0.37 8 0.490.52 0.54 0.27 0.28 Dynamic 1 0.36 0.42 0.30 0.20 0.21 2 0.23 0.41 0.310.16 0.20 3 0.65 0.60 0.52 0.53 0.47 4 0.45 0.53 0.45 0.22 0.29 5 0.440.55 0.52 0.30 0.40 6 0.28 0.41 0.33 0.16 0.18 7 0.60 0.58 0.61 0.590.41 8 0.46 0.54 0.51 0.26 0.27

The sealing compatibility of the naked collation film of the inventionto itself was 5 investigated, with the following results.

TABLE 4 Heat Seal Threshold (g/25 mm) Samples were sealed @ 5 psi for0.2 second dwell metal/rubber 10 (Bottom jaw off/top jaw 80° C.-130°C.). Example 80° C. 85° C. 90° C. 95° C. 100° C. 105° C. 110° C. 115° C.120° C. 125° C. 130° C. IN/OUT 1 0 0 0 13 11 42 306 128 364 505 449 2 00 0 0 0 0 6 8 113 14 141 3 0 0 0 0 5 10 6 342 355 353 339 4 0 0 7 8 80263 405 472 376 455 504 5 0 0 0 0 0 0 0 4 26 8 16 6 0 0 0 0 0 6 11 15 12133 54 7 0 0 0 0 7 4 24 157 448 490 503 8 0 0 0 0 11 14 257 547 384 388461 OUT/OUT 1 7 20 30 87 100 200 179 221 257 261 290 2 0 0 4 10 35 174368 438 360 466 399 3 0 3 4 4 15 13 24 238 321 445 423 4 0 0 5 20 126353 394 467 431 375 406 5 0 2 3 4 5 5 8 261 295 241 505 6 0 0 2 3 35 38160 263 326 294 460 7 0 0 2 4 4 5 93 356 306 353 263 8 0 0 3 9 97 366448 427 408 403 470

To investigate the degree of incompatibility between the naked collationfilm of the invention and the film used on the unit wraps, heat sealthresholds were carried using the ‘Hybrid’ three film seal test. Theinner seal of the naked collation film of the invention seal is testedagainst the outer off the unit wrap, with bottom jaw off. The unit wrapfilms selected for this test were GLS20, GLT20, and XLT20, allpolyolefinic unit wrap films available from Innovia Films Ltd, Wigton,Cumbria.

TABLE 5 Hybrid Heat Seal Threshold These tables show the out/in sealstrength of the naked collation film and the strength of inner (nakedcollation) to outer of (unit wrap GLS20/GLT20/XLT20) for each variant.Example 80° C. 85° C. 90° C. 95° C. 100° C. 105° C. 110° C. 115° C. 120°C. 125° C. 130° C. OUT/IN

 GLS20 OUT EXAMPLE 0 0 0 0 6 68 193 268 334 340 407 1 Out/In EXAMPLE 0 00 0 0 0 1 0 28 24 11 1 OUT/IN

 GLS20 OUT EXAMPLE 0 0 0 0 0 6 25 27 121 35 240 2 Out/In EXAMPLE 0 0 0 00 0 0 0 0 0 44 2 OUT/IN

 GLS20 OUT EXAMPLE 0 0 0 0 2 7 20 270 350 341 385 3 Out/In EXAMPLE 0 0 00 0 0 0 19 46 92 20 3 OUT/IN

 GLS20 OUT EXAMPLE 0 0 0 0 68 99 335 478 467 465 339 4 Out/In EXAMPLE 00 0 0 0 0 1 12 10 38 49 4 OUT/IN

 GLS20 OUT EXAMPLE 0 0 0 0 0 2 5 5 4 12 12 5 Out/In EXAMPLE 0 0 0 0 0 00 0 0 0 0 5 OUT/IN

 GLS20 OUT EXAMPLE 0 0 0 0 1 7 7 27 18 155 150 6 Out/In EXAMPLE 0 0 0 00 0 0 0 0 0 0 6 OUT/IN

 GLS20 OUT EXAMPLE 0 0 0 0 0 2 20 16 128 213 300 7 Out/In EXAMPLE 0 0 00 0 0 0 0 0 17 96 7 OUT/IN

 GLS20 OUT EXAMPLE 0 0 0 2 7 22 66 308 467 447 343 8 Out/In EXAMPLE 0 00 0 0 0 0 0 0 16 59 8 OUT/IN

 GLS20 OUT OUT/IN

 GLT20 OUT EXAMPLE 0 0 0 0 5 95 184 215 264 247 297 1 Out/In EXAMPLE 0 00 0 0 0 0 0 0 0 7 1 OUT/IN

 GLT20 OUT EXAMPLE 0 0 0 0 0 2 17 81 47 102 23 2 Out/In EXAMPLE 0 0 0 00 0 0 0 0 0 0 2 OUT/IN

 GLT20 OUT EXAMPLE 0 0 0 0 4 15 5 119 99 36 216 3 Out/In EXAMPLE 0 0 0 00 0 0 9 9 11 16 3 OUT/IN

 GLT20 OUT EXAMPLE 0 0 0 0 60 409 483 441 449 494 451 4 Out/In EXAMPLE 00 0 0 0 9 3 9 27 24 96 4 OUT/IN

 GLT20 OUT EXAMPLE 0 0 0 0 0 0 2 3 4 27 12 5 Out/In EXAMPLE 0 0 0 0 0 00 0 0 0 0 5 OUT/IN

 GLT20 OUT EXAMPLE 0 0 0 0 0 5 14 131 48 21 81 6 Out/In EXAMPLE 0 0 0 00 0 0 0 0 0 0 6 OUT/IN

 GLT20 OUT EXAMPLE 0 0 0 0 4 3 142 11 132 57 53 7 Out/In EXAMPLE 0 0 0 00 0 0 0 8 4 9 7 OUT/IN

 GLT20 OUT EXAMPLE 0 0 0 2 8 141 331 349 354 158 454 8 Out/In EXAMPLE 00 0 0 0 0 0 0 6 15 17 8 OUT/IN

 GLT20 OUT OUT/IN

XLT20 OUT EXAMPLE 0 0 0 3 8 34 139 213 289 312 325 1 Out/In EXAMPLE 0 00 0 0 0 0 0 0 1 3 1 OUT/IN

XLT20 OUT EXAMPLE 0 0 0 0 2 7 34 29 14 11 26 2 Out/In EXAMPLE 0 0 0 0 00 0 0 0 0 0 2 OUT/IN

 XLT20 OUT EXAMPLE 0 0 0 3 4 50 9 123 287 269 208 3 Out/In EXAMPLE 0 0 00 0 0 0 94 26 16 70 3 OUT/IN

 XLT20 OUT EXAMPLE 0 3 8 19  125 395 342 393 406 364 483 4 Out/InEXAMPLE 0 0 0 0 0 0 0 9 10 27 169 4 OUT/IN

 XLT20 OUT EXAMPLE 0 0 0 0 2 1 2 4 7 7 7 5 Out/In EXAMPLE 0 0 0 0 0 0 00 0 0 0 5 OUT/IN

 XLT20 OUT EXAMPLE 0 0 0 0 2 3 5 10 28 12 22 6 Out/In EXAMPLE 0 0 0 0 00 0 0 0 0 0 6 OUT/IN

 XLT20 OUT EXAMPLE 0 0 0 0 2 4 4 213 90 32 43 7 Out/In EXAMPLE 0 0 0 0 00 0 0 5 2 9 7 OUT/IN

 XLT20 OUT EXAMPLE 0 0 2 3 8 15 69 316 154 257 464 8 Out/In EXAMPLE 0 00 0 0 0 0 0 7 12 18 8 OUT/IN

 XLT20 OUT

Examples 9 to 12

The films were prepared in the same manner as the films of Examples 1 to8 and the film compositions are presented in Table 6:

TABLE 6 Sample Details Discharge Example Inner Coat Outer Coat Treatment9 0.20 μm thickness, 0.30 μm thickness, Non comprising a physicalcomprising a Treated blend of SPX78J3 + physical blend of 0.04% silica +0.175% SPX78J3^(#) + 0.1% silicone gum + 10% silica + 0.5% C600H2silicone gum 10 0.20 μm thickness, 0.30 μm thickness, Non comprising aphysical comprising a Treated blend of BP physical blend BP LL2640AC¹LLDPE + LL2640AC LLDPE + 0.09% silica + 0.09% 0.09% silica + SILICONEGUM 0.09% silicone gum 11 0.20 μm thickness, 0.30 μm thickness, Noncomprising comprising Treated XM7080^(†)/Adsyl^(!) +XM7080^(†)/Adsyl^(!) + 1.5% silicone + 1.5% silicone + 0.4% silica 0.4%silica 12 0.50 μm thickness, 0.50 μm thickness, Non comprisingcomprising Treated XM7080^(†)/Adsyl^(!) XM7080^(†)/Adsyl^(!) (50:50)(50:50) !a commercial grade of LLDPE supplied by BP (now Ineos),Belgium. N. V. Rue de Ransbeek, 310 B-1120, Brussels. †a randompropylene ethylene butylene (terpolymer), supplied by Basell PolyolefinsCompany NV. Avenue J. Monnet 1, B-1348 Ottignes, Louvain-la-Neuve.

a metallocene catalysed propylene-ethylene co-polymer, supplied byMitsui Chemicals Inc. Shiodome City Center, 5-2, Higashi-Shmbashi1-chome, Minato-ku, Tokyo 105-7117, Japan.

Certain mechanical and optical properties of the films were measured,with the following results:

TABLE 7 Optics Narrow Wide Gloss % (45°) Angle Angle Sample IN OUT Haze(%) Haze (%) 9  98.5-100.2  98.5-100.3 0-1 0.9-1.1 10 102.3-104.5103.8-105.2 0-1 0.9-1.0 11 95.4-96.4 95.1-96.4 1-2 2.0-2.2 12 96.6-97.797.6-98.6 6-7 1.4-1.4

TABLE 8 Coefficient of Friction Static EXAMPLE IN/IN OUT/OUT IN/OUT 90.45 0.37 0.34 10 0.62 0.54 0.43 11 0.29 0.25 0.27 12 0.15 0.18 0.16Dynamic EXAMPLE IN/IN OUT/OUT IN/OUT 9 0.39 0.32 0.30 10 0.37 0.39 0.4111 0.16 0.16 0.15 12 0.12 0.17 0.14 Samples were tested on the Messmerslip tester using the Clampmod method.

The sealing compatibility of the naked collation film of the inventionto itself was investigated, with the following results.

TABLE 9 Heat Seal Threshold (g/25 mm) Samples were sealed @ 5 psi for0.2 second dwell metal/rubber (Bottom jaw off/ top jaw 100° C.-140° C.)Example 100° C. 105° C. 110° C. 115° C. 120° C. 125° C. 130° C. 135° C.140° C. IN/IN 9 0 0 0 96 101 399 339 349 360 10 0 281 342 337 366 437352 412 342 11 0 0 112 181 146 189 184 233 302 12 234 279 322 371 386369 383 433 402 OUT/OUT 9 0 0 113 398 343 349 410 411 400 10 0 244 315398 343 368 363 330 360 11 0 123 157 142 321 289 328 325 315 12 212 232302 372 386 389 406 433 412 IN/OUT 9 0 0 50 116 384 352 346 404 479 10 0308 321 277 295 354 315 362 434 11 0 119 167 182 330 353 361 366 442 12281 311 342 396 406 419 405 433 412

To investigate the degree of incompatibility between the naked collationfilm of the invention and the film used on the unit wraps, heat sealthresholds are carried are using the ‘Hybrid’ three film seal test. Theinner seal of the naked collation film of the invention seal is testedagainst the outer off the unit wrap, with bottom jaw off. The unit wrapfilms selected for this test are GLS20, GLT20, and XLT20, allpolyolefinic units wrap films available from Innovia Films Ltd, Wigton,Cumbria, and the films of Examples 9 to 12 are found to be sealinglyincompatible with the unit wrap films.

1. A method for forming a naked collation package comprising: a.providing an arrangement of packages individually wrapped in a filmicpolyolefinic material; b. providing a naked collation film for nakedlywrapping said individually wrapped packages, the naked collation filmcomprising a polyolefinic core layer C, a polyolefinic inner sealinglayer A on the inner surface of the naked collation film and apolyolefinic outer sealing layer B on the outer surface of the nakedcollation film, the polyolefinic material of the inner sealing layer Abeing selected for sealing incompatibility with the filmic polyolefinicmaterial of the individually wrapped packages under a specified sealingcondition, and the polyolefinic material of the outer sealing layer Bbeing selected for sealing compatibility with B and for sealingcompatibility with A under the selected sealing condition, wherein theexternal surface of the filmic polyolefinic material of the individuallywrapped packages comprises at least one polyolefinic component derivedfrom a monomeric olefin having a carbon chain length x, and thepolyolefinic material of the inner sealing layer A comprises at leastone polyolefinic component derived from a monomeric olefin having acarbon chain length y, y being different from x; c. arranging theindividually wrapped packages in an ordered configuration in contactwith polyolefinic sealing layer A of the naked collation film; d.wrapping the naked collation film around the ordered configuration ofindividually wrapped packages to form a film tube with overlappingedges; e. forming a girth seal by sealing together the overlapping edgesof the film tube, without sealing inner sealing layer A to the filmicpolymeric material of the individually wrapped packages; and f. formingenvelope seals at each end of the package by folding in the film tubeand sealing the folded ends, without sealing inner sealing layer A tothe filmic polymeric material of the individually wrapped packages.
 2. Amethod according to claim 1, wherein the polymeric material of the innersealing layer comprises at least one polyolefinic component having a lowheat seal threshold.
 3. A method according to claim 1, wherein thepolymeric material of the outer sealing layer comprises at least onepolyolefinic component having a low heat seal threshold.
 4. A methodaccording to claim 1, wherein the polyolefinic material of the outersealing layer B also comprises at least one polyolefinic componentderived from a monomeric olefin having a carbon chain length y.
 5. Amethod according to claim 1, wherein both x and y are from 2 to
 4. 6. Amethod according to claim 1, wherein the sealing condition comprisesconditions of elevated temperature and/or pressure and a dwell time forthe sealing operation.
 7. A method according to claim 6, wherein thesealing temperature is above 80° C.
 8. A method according to claim 6,wherein the sealing temperature is below 200° C.
 9. A method accordingto claim 6, wherein the dwell time is from 0.05 s to 2 s.
 10. A nakedcollation package manufactured by a method according to claim
 1. 11. Anaked collation package comprising an arrangement of individualpackages, individually packaged in a polyolefinic filmic material, thatare packed together in said naked collation package in a naked collationfilm, wherein the naked collation film comprises a sealable polyolefinfilm having a polyolefinic core layer C, an polyolefinic inner sealinglayer A and a polyolefinic outer sealing layer B, the polyolefinicmaterial of the inner sealing layer A being selected for sealingincompatibility with the filmic polyolefinic material of the individualpackages under a specified sealing condition, and the polyolefinicmaterial of the outer sealing layer B being selected for sealingcompatibility with B and for sealing compatibility with A under theselected sealing condition, wherein the external surface of the filmicpolyolefinic material of the individually wrapped packages comprises atleast one polyolefinic component derived from a monomeric olefin havinga carbon chain length x, and the polyolefinic material of the innersealing layer A comprises at least one polyolefinic component derivedfrom a monomeric olefin having a carbon chain length y, y beingdifferent from x, the individual packages being arranged in an orderedconfiguration inside the package and with the naked collation filmwrapped around the ordered configuration of individual packages andsealed to itself at a girth seal, and sealed to itself at envelope sealsat each end of the package, there being no seal between the nakedcollation film and the filmic material of the individual packages. 12.The naked collation package according to claim 11, wherein the polymericmaterial of the inner sealing layer comprises at least one polyolefiniccomponent having a low heat seal threshold.
 13. The naked collationpackage according to claim 11, wherein the polymeric material of theouter sealing layer comprises at least one polyolefinic component havinga low heat seal threshold.
 14. The naked collation package according toclaim 11, wherein the polyolefinic material of the outer sealing layer Balso comprises at least one polyolefinic component derived from amonomeric olefin having a carbon chain length y.
 15. The naked collationpackage according to claim 11, wherein both x and y are from 2 to
 4. 16.The naked collation package according to claim 11, wherein the nakedcollation film has a thickness of from about 10 μm to about 240 μm. 17.The naked collation package according to claim 11, wherein each sealinglayer in the naked collation film has a thickness of from about 0.05 μmto about 2 μm.
 18. The naked collation package according to claim 11,wherein the core layer comprises a homopolymer.
 19. The naked collationpackage according to claim 11, wherein the naked collation film furthercomprises a barrier layer.
 20. The naked collation package according toclaim 11, wherein the naked collation film comprises a biaxiallyorientated polypropylene (BOPP) film.